1. Field of the Invention
This invention relate to silver wires for use in video display apparatus such as VTR or TV or in audio equipment.
2. Background Information
Conductors conventionally used in recording, acoustic or image transmission applications are made of annealed copper wires, which are produced by cold working oxygen-free or tough pitch copper with a purity of about 99.9 wt % followed by annealing, or copper wires prepared by plating such annealed copper wires.
With copper wires having purities on the order of 99.9 wt %, signals cannot be transmitted correctly without phase differences and, as a result, only blurred images or unsharp sounds are produced. To solve these problems, high-purity copper wires produced by working raw materials having purities of at least 99.999 wt % have recently been introduced into the market.
Similar effects are exhibited by silver wires that are produced by a process which comprises solidifying silver with a purity of at least 99.95 wt % in one longitudinal direction to yield an ingot, drawing it by either cold or warm working and further working the wire under conditions that will not cause recrystallization. This process is described in Unexamined Published Japanese Patent Application No.163505/1986 under the title of "A Process for Producing Conductors for Use in Video Display Apparatus or Audio Equipment". However, the demand of the market has solely been for high-purity copper wires.
Thus, in the metal purifying technology, 6N and 7N copper materials have successfully been developed (purities of at least 99.9999 wt % will hereunder be designated as "6N" and purities of at least 99.99999 wt % as "7N"); on the other hand, practically feasible methods of purifying silver materials are yet to be developed and no silver wires of high purity have been produced that can be tested for their performance to thereby obtain data that compare with high-purity copper wires.